Coral Reefs and Islands. 273 



have taken place in the ocean were not crowded events of a 

 short period. 



Moreover, these local elevations in coral-seas are spread 

 over an area of 25,000,000 square miles. As an example of 

 the long distances, the Paumotu Archipelago, consisting of 

 more than eighty atolls and two barrier-islands, and covering 

 about 450,000 square miles, contains only three or four 

 atolls that are over twelve feet high ; and of these, Metia is 

 250 feet in height, Elizabeth 80 feet, Dean's, probably where 

 highest, 15 or 20 feet. Metia is one of the westernmost, near 

 148° 13 / W. and 15° 50' S.; Dean's is 60 miles to the north- 

 north-east of Metia, and Elizabeth is far to the south-east, in 

 128° W. and 25° 50'' S., or nearly 1450 miles distant from 

 Metia. Locate these points on a continent, and Pacific 

 distances and the length of Pacific chains of atolls will be 

 appreciated. 



IV. No Ancient Coral-reefs have the Thickness attributed by the 

 Subsidence- Theory to Modern Reefs. 



An argument against the subsidence-theory is based by 

 Prof. J. J. Rein* on the alleged fact that the thickness 

 attributed to modern reefs is far beyond that of any such 

 reefs in earlier time ; that is, the thickness is unprecedented. 

 The argument decides nothing. The question is one of 

 geological fact, not to be settled by a precedent. Whether, 

 then, there are precedents or not it is not necessary to 

 consider. 



Besides this, it implies a distinction between coral-made 

 and shell-made rocks which does not exist. The coral-reef 

 rock is largely made of shells, and the process of formation 

 for a limestone of shallow-sea origin is essentially the same 

 whether shells or corals are predominant or the sole material. 

 No thick formation of any kind of rock was ever made, or 

 could be made, by shore or shallow-sea operations without a 

 slowly continued subsidence or a corresponding change of 

 water-level. 



V. Other Methods of Explanation, and their Supporting 

 Evidence. 



A. Mr. John Murray, one of the able naturalists of the 

 ' Challenger ' expedition, reports the following important results 



* Dr. Rein's first memoir on Bermuda appeared in the Senckenberg 

 Ber. naturforsch. Gesellschaft, 1869-70, p. 857, and the later in the 

 Verhandlung des I. deutsch. Geographentages, 1881, Berlin, 1882. The 

 above argument is from the latter paper, and is given here from the 

 citation by Dr. Geikie, the publication not being accessible to the writer. 



